Here’s how even occasional binge drinking can have big health consequences
Americans are drinking less than they have in decades. But a new study on mice shows even one bottomless brunch may shrink the small intestine’s nutrient-absorbing surface and spark inflammation that reaches the brain.
A bottomless brunch or a few extra drinks after work may feel harmless. But new research in mice suggests that within hours of binge drinking (approximately four drinks for women or five for men within about two hours), the small intestine’s structure begins to shift.
In the study, published in November 2025, researchers observed shortened villi—the finger-like projections that expand the gut’s surface area for nutrient absorption—along with a surge of inflammatory immune cells. Even 24 hours later, inflammatory markers remained significantly elevated, suggesting the intestine had not fully recovered.
Scientists have long linked chronic alcohol use to so-called “leaky gut,” a condition in which the intestinal barrier becomes more permeable. While the findings were observed in mice, prior human studies have linked heavy drinking to increased intestinal permeability and systemic inflammation. Researchers say the new data adds insight into how quickly that damage may begin.
The results also suggest the gut may be among the first organs to react to alcohol, potentially setting off inflammatory changes well before longer-term damage becomes visible.
The gut’s protective barrier can act like skin
Diego Bohórquez, a professor of medicine and neurobiology at Duke University who studies the gut-brain connection, describes the intestine as something of an external organ. “The epithelial layer is the skin of the gut,” he says. “When you add something as strong and caustic as alcohol you're technically exposing the inside of the body.”
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In the study, researchers saw that disruption play out at the microscopic level. The epithelial cells live on finger-like structures within the small intestine called villi, which help to expand the small intestine’s surface area. “What they’re seeing at a global level is the length of the villus is decreasing three hours after the binge,” says Laura Rupprecht, who leads the Gut-Brain Biology Lab at the University of North Carolina at Chapel Hill. Because villi increase the intestine’s surface area, shortening them may reduce the gut’s ability to absorb nutrients and could weaken the barrier that keeps bacteria and toxins contained.
Researchers assessed the mice three hours and 24 hours after the binge. “Twenty-four hours after the binge, there is still a significant decrease, but the general structure of the villus looks a bit restored, and some of the inflammation markers they’re looking at are very elevated,” Rupprecht adds.
Alongside structural changes, researchers observed an influx of neutrophils, immune cells typically used to fight infections. However, when activated without a pathogen to fight, they can damage surrounding tissue.
“Those bacteria are then able to leave the intestine and cause inflammation in other parts of the body, and particularly in the brain,” she says, a process seen in prior studies of heavy alcohol use. “That inflammation in the brain that comes from the intestine is thought to perpetuate some of that alcohol over consumption.”
(Here are eight things we’ve learned about how alcohol harms the body.)
Inflammation itself is not inherently harmful. It is the body’s natural response to infection, injury, or toxins. “It means that your body and your immune system is activated,” Shauna McQueen, a registered dietitian and founder of Food School, a culinary education platform designed specifically for registered dietitians and nutrition professionals, says. “It could be part of a completely normal response until we get to that point where it is chronic inflammation, and that starts impacting how everything is functioning.”
The problem arises when that response becomes chronic. Over time, persistent inflammation can alter metabolism, increase oxidative stress, and contribute to conditions such as cardiovascular disease, neurodegeneration, and cancer. “Your body will constantly prioritize that inflammation. The load becomes a lot, and other things can end up suffering because they don't,” she says.
Can the gut recover?
In the study, villi appeared partially restored by 24 hours, suggesting the gut can begin repairing itself — though inflammation remained elevated.
While there isn’t a clear-cut way to instantly repair an injured epithelial layer, McQueen says the gut is more adaptable than many people realize. “What’s interesting when it comes to gut health is the makeup of your gut can change pretty quickly—within a few days of changing your diet—the bacterial profile in your gut can start to change,” she says.
(If you’re going to drink, what’s the ‘healthiest’ way to do it?)
Supporting that shift, says McQueen, means focusing on fiber-rich whole foods that act as prebiotics—fuel for beneficial gut bacteria—such as fruits, vegetables, whole grains, and oats. Fermented foods, including yogurt, kefir, kimchi, and kombucha, can introduce probiotics, or live microbes that may help diversify the gut ecosystem. “There’s also really cool research on movement and how being active can impact your gut and the bacterial profile, so it’s another piece to the puzzle,” McQueen says.
Ultimately, the most effective way to protect the gut from alcohol-related injury is to limit exposure. While abstaining offers the clearest benefit, experts say moderation, typically defined in U.S. dietary guidelines as up to one drink per day for women and two for men, is a practical and meaningful step for those who choose to drink.
